Method and Device for Separating and Conveying a Number of Flat Objects

ABSTRACT

A device ( 2 ) is described for separating and conveying towards a packaging station ( 5 ) a predetermined number of flat objects fed in piles ( 13. 13 ′) by a folding unit ( 1 ). The device ( 2 ) comprises: a conveying surface ( 20, 120 ) provided with a plurality of slots ( 21 ), a plurality of shoes or carriages ( 24 ) which support a plurality of racks ( 31 ) moveable from a lowered position to a raised position in which the prongs ( 32 ) of the racks pass through the slots ( 21 ) of the conveying surface ( 20, 120 ) to protrude upward therefrom. A predetermined number of flat objects are separated from a pile ( 13, 13 ′) being formed to form a pack ( 113, 113 ′) between a pair of racks ( 31 ) supported by a pair of carriages ( 24 ), which are made to translate so as to convey the pack ( 113, 113 ′) towards the packaging station ( 5 ).

The present invention refers to a method and to a device for separating and conveying towards a packaging station a predetermined number of flat objects, such as strips or sheets of paper set down by a folding machine, such as a machine for forming table tissues. More in particular, the present invention concerns the separation and the transfer of strips or of sheets of paper during setting down or formation thereof to obtain in a mechanized manner packs comprising a predetermined number of table tissues or the like.

The description that follows will be provided using as an example table tissues, but it is to be understood that it is not intended to restrict the application of the invention only to table tissues.

Manufacture of table tissues is currently done by means of folding machines, which essentially comprise two counter-rotating rollers, pushing means and a cutting blade. The paper web reaching the rollers from the master roll is gripped by a gripper present on one of the counter-rotating rollers and pulled on the surface of the mentioned roller, up to a certain position in which the gripper releases its grip leaving a folded flap. A similar gripper present on the other roller in turn performs a similar operation, forming an identical flap on the other side downstream from the pair of rollers and so on in succession, so as to put down flaps of paper one after another to the right and to the left downstream of the rollers to form a zigzag folded paper web.

Pushing means consisting of curved rods or the like are housed in appropriate recessed seats formed on the side surface of the rollers and are driven out of the seats after formation of each flap, moving the flaps away from the folded web to make room each time for the incoming new flap. The pushing means press the flaps against a blade, which cuts the folded web in half, dividing it into two piles of table tissues side by side.

Up to this point the processing is mechanized and proceeds at very high rates. Problems arise when it is necessary to pick up the table tissues from the pile and to divide them into a pack of a predetermined number.

Separating devices are known in the form of fingers which are inserted into the pile of table tissues to separate a certain number of tissues so as to form a pack containing a small number of tissues which is picked up with appropriate grippers or tipped over on the plain of 90°. However, this separating device proves inadequate for separating and in particular for picking up and for conveying a large number of tissues towards a packaging station for the formation of family-size packs, that is to say of packs containing a large number of tissues. As a result, in order to form family-size packs, the operator must manually separate and pick up the tissues in the packaging station with a resulting waste of time and of labour and a slowing of the production cycle of the machine.

Object of the present invention is to eliminate the drawbacks of the prior art by providing a method and a device for separating and for conveying towards the packaging a predetermined number of flat objects, such as sheets of paper, particularly tissues, that are able to automate and to speed up the production cycle of the packs of flat objects.

Another object is to provide such a method and such a device that are particularly suitable to be employed for the production of family-size packs consisting of a large number of flat objects.

Yet another object is to provide such a method and such a device that are highly versatile and suitable to be applied to various types of machines for the production of flat objects, such as sheets of paper, table tissues and the like.

Yet another object is to provide such a device that is inexpensive and simple to make.

These objects are achieved according to the invention with the device and the method whose characteristics are listed respectively in appended independent claims 1 and 14.

Advantageous embodiments of the invention will be apparent from the dependent claims.

According to the invention the device for separating and for conveying towards a packaging station a predetermined number of flat objects, fed in piles from a folding unit, comprises:

-   -   a conveying surface provided with a plurality of longitudinal         through slots,     -   a plurality of shoes or carriages mounted slidably on guides         beneath the conveying surface, and     -   a plurality of racks mounted movably on said carriages to pass         from a lowered position beneath the conveying surface to a         raised position in which the prongs of the racks pass through         the longitudinal slots of the conveyor surface to protrude         upward therefrom.

The racks are operated so as to separate a predetermined number of flat objects from a pile being formed, to form a pack between a pair of racks supported by a respective pair of carriages which are made to translate on their guides so as to convey the pack towards the packaging station.

The carriages of a pair can preferably be made integral with each other, so as to operate a single carriage to convey the pack comprised between the two racks supported by the two carriages.

With said device it is possible to position a plurality of pairs of carriages, which act alternately on a conveyor line so as to be able to continuously convey packs of flat objects from the folding station towards the packaging station.

Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplary and therefore non-limiting embodiment thereof, illustrated in the appended drawings, in which:

FIG. 1 is a top plan view, partially broken away, showing a machine for the production of table tissues provided with the separating and conveying device according to the invention;

FIG. 2 is a side elevational view of the machine of FIG. 1, partially broken away;

FIG. 3 is an enlarged cross sectional view, taken along the plane of section III-III of FIG. 1, illustrating the separating and conveying device according to the invention;

FIG. 4 is an enlarged cross sectional view, taken along the plane of section IV-IV of FIG. 1, showing the packaging station of the machine for the production of tissues of FIG. 1;

FIG. 5 is a perspective view showing diagrammatically the separating and conveying device according to the invention in an initial step of the cycle;

FIG. 6 is a diagrammatic perspective view, like FIG. 5, in which the separating and conveying device has performed the separation of two groups of table tissues;

FIG. 7 is the enlarged view of a detail of FIG. 6;

FIG. 8 is a diagrammatic perspective view, like FIG. 6, in which the separating and conveying device has performed the transfer of two groups of table tissues into the packaging station;

FIG. 9 is a side elevational view of FIG. 8, but showing the step of compressing the packs of table tissues;

FIG. 10 is an enlarged perspective view rotated 180° with respect to FIG. 8, showing the packaging station in the step of compressing two packs of table tissues;

FIG. 11 is a view like FIG. 10, but in the step of ejecting the first pack of table tissues;

FIG. 12 is a view like FIG. 11, but in the step of moving the second pack of table tissues;

FIG. 13 is a view like FIG. 12, but in the step of ejecting the second pack of table tissues; and

FIG. 14 is a perspective view like FIG. 8, in which the packaging station is in the step of ejecting the second pack of table tissues.

For now, with reference to FIGS. 1 and 2 a machine for the production of packs of table tissues, indicated as a whole with the reference numeral 100, is described.

The machine 100 shown in the figures comprises two parallel production lines, each comprising:

-   -   a folding unit 1 for the formation of the table tissues,     -   a separating and conveying device 2 for the separation of the         table tissues into predetermined groups and for the transfer of         said groups,     -   a packaging station 5 for compressing said groups of table         tissues into packs, and     -   a conveyor 7, shared by the two production lines, for conveying         the packs towards a packaging station.

Since the two production lines are perfectly symmetrical, only one will be described hereunder.

The folding unit 1 comprises a pair of counter-rotating rollers 10 and 10′ disposed with vertical axes. The paper web 11 coming from a master roll and already folded in two by a tip (not shown) disposed upstream passes through the rollers 10 and 10′ which, by means of grippers, zigzag fold it in a known manner. At each rotation of the rollers 10 and 10′ a first folded flap 12, opposite the roller 10, and a second folded flap 12′, opposite the roller 10′, are formed.

In order to leave the necessary space for the incoming flaps, the already formed flaps 12 and 12′ are pushed forward by means of pressers formed by arched bars housed in circumferential recessed seats in the surface of the rollers 10 and 10′. At the same time the pressers push the flaps towards a cutting blade (112, 112′) disposed longitudinally so as to divide the flaps into two piles of table tissues 13 and 13′ separated and placed side by side.

As also shown in FIG. 5, the piles 13 and 13′ of table tissues accumulate on a horizontal collecting surface 14 which continues in a slightly downwardly sloping conveying surface 20, forming part of the separating and conveying device 2.

Above the horizontal collecting surface 14 and near to the beginning of the sloping conveying surface 20, there are provided a pair of separator-pushers 19. Each separator-pusher 19 comprises a block 15 integral with the frame of the machine that supports a cylinder 16 within which a rod 17 is mounted slidably and rotatably with its axis parallel to the direction of travel of the tissues. The head of the rod 17 is integral with one end of a pushing and separating plate 18. The rod 17 can pass from a retracted position inside the cylinder 16 to an extracted position outside the cylinder 16 and the plate 18 can pass, by a 90° rotation of the rod 17, from a resting position in which it protrudes laterally outward to a working position in which it protrudes downward, dividing the relative pile 13 and 13′ transversally.

The separating and conveying device 2 according to the invention is described hereunder with reference to FIGS. 1, 2, 3 and 5.

The sloping conveying surface 20 comprises a plurality of longitudinal through slots 21, equidistant with respect to a midline. Even if only four slots 21 are illustrated in FIG. 1 for reasons of clarity, the longitudinal slots 21 are preferably six in number as shown in FIGS. 3 and 5.

Beneath the sloping surface 20, the device 2 comprises a linear guide consisting of a pair of guide bars 22 and 22′ having a substantially rectangular cross section. The guide bars 22 and 22′ are disposed parallel to each other on a plane parallel to the sloping conveying surface 20 and are spaced apart from each other so as to leave a space 23. The guide bars 22 and 22′ are mounted fixed on the frame 24 of the machine.

Four shoes or carriages 24 are mounted slidably on each guide bar 22 and 22′. To be precise, the pairs of carriages 24 a, 24 b and 24 a′, 24 b′ are mounted respectively on the outer sides of the bars 22 and 22′, whilst the pairs of carriages 24 c, 24 d and 24 c′, 24 d′ are mounted respectively on the inner sides of the bars 22 and 22′, that is to say in the space 23. Thus, a respective pair of carriages 24 is mounted on each side of the bars 22 and 22′.

As shown in FIG. 3, each carriage 24 has a set of upper and lower wheels 25 which run on rails 125 disposed respectively on the top and on the bottom surface of each guide bar 22 and 22′.

Returning to FIG. 5, the rear carriages (24 a, 24 a′, 24 c, 24 c′) of each pair have at the bottom a block 26 which integrally supports a rod 27, circular in section, disposed beneath the guide bars 22 and 22′ and with its axis parallel to the axis of the guide bars 22 and 22′. The front carriages (24 b, 24 b′, 24 d, 24 d′) of each pair, on the other hand, have at the bottom a cylindrical sleeve 28 which is mounted slidably on the respective rods 27. Jaw means (not shown) are provided inside the sleeve 28 of the front carriages to lock the sleeve 28 on the rod 27. Clearly the rods 27 can extend for a greater length with respect to that illustrated in FIGS. 2 and 5.

The front carriages (24 b, 24 b′, 24 d, 24 d′) are motorized independently, by means of respective belt or chain transmissions 40 (FIG. 2) driven by respective pulleys 41 disposed at the front and at the rear end of the guide bars 22 and 22′.

A shaft 29 of a linear actuator is mounted slidably in each carriage 24, with its axis substantially at right angles to the sloping conveying surface 20. The shaft 29 can pass from a retracted position inside the carriage 24 to an extracted position in which it protrudes upward from the carriage until it arrives near the sloping conveyor surface 20.

On the head of each shaft 29 a transverse supporting bar 30, which extends for about half the width of the sloping conveyor surface 20, cantilevers. Clearly the transverse supporting bars 30 of the carriages (24 a, 24 a′, 24 b, 24 b′) disposed on the outer sides of the guide bars 22 and 22′ cantilever inwards, whereas the transverse supporting bars 30 of the carriages (24 c, 24 c′, 24 d, 24 d′) disposed on the inner sides of the guide bars 22 and 22′ cantilever outwards.

On each transverse supporting bar 30 is mounted a rack 31 comprising three upward protruding prongs 32, equidistant from each other and in register with the respective longitudinal slots 21 of the sloping conveying surface 20. In this manner, when the shaft 29 is in the retracted position, the rack 31 is beneath the sloping conveying surface 20, whereas when the shaft 29 is in the extracted position, the prongs 32 of the rack 31 pass through the longitudinal slots 21 of the sloping conveying surface and protrude upward therefrom.

It should be noted that the racks 31 of the carriages mounted on the first guide bar 22 acts on a first row of three slots 21 on the conveying surface 20, whereas the racks 31 of the carriages mounted on the second guide bar 22′ act on a second row of three slots 21 on the conveying surface 20.

Furthermore, it should be noted that the length of the prongs 32 of each rack 31 is slightly less than the length of each shaft 29 of the actuator of the carriage 24, when the shaft 29 is extracted from the respective carriage 24.

The sloping conveying surface 20 has a tilting terminal portion 120 hinged thereto in a pivot axis 121 and disposed beneath the packaging station 5. The tilting surface 120 is moved around the pivot axis 121 by a linear actuator 122 (FIG. 2) comprising a cylinder 123 and a piston 124, in which the head of the piston 124 is integral with the end of the tilting surface 120. In this manner the piston 124 moves from a retracted position in which the tilting surface 120 is parallel to the sloping surface 20 to an extracted position in which the tilting surface 120 is parallel to the horizontal.

Naturally, the conveying surface 20, which in the embodiment illustrated is mounted sloping, could also be horizontal, in which case the tilting terminal portion 120 would not be necessary.

The packaging station 5 will be described with the aid of FIGS. 1, 2, 4 and 5.

The packaging station 5 is disposed above the tilting surface 120 and comprises a front plate 50, a rear plate 51 and a top plate 52, to which two side plates 53 and 54 are connected integrally.

The front plate 50 is disposed along a vertical plane and transversally with respect to the tilting surface 120 and is moved along a vertical axis by means of a linear actuator 58 comprising a cylinder 57 and a piston 56. The cylinder 57 of the actuator 58 is integral with the frame of the machine and the head of the piston 56 is made integral with the front plate 50 by means of a block 55.

The rear plate 51 is disposed along a vertical plane and transversally with respect to the tilting surface 120 and is moved along a horizontal axis by means of a linear actuator 59 comprising a cylinder 60 and a piston 61. The cylinder 60 of the actuator 59 is integral with the frame of the machine and the head of the piston 61 is integral with the rear plate 51.

The top plate 52 is disposed along a horizontal plane and is moved along a vertical axis by means of a linear actuator 62 comprising a cylinder 63 and a piston 64. The cylinder 63 of the actuator 62 is integral with a support 65, which is mounted transversally slidable on an arm 66 integral with the frame of the machine. The head of the piston 64 is integral with the top plate 52. The width of the top plate 52 is equal to about half the width of the tilting conveying surface 120 and the side plates 53, 54, which are disposed vertically in a longitudinal direction with respect to the tilting conveying surface 120, are mounted integrally at its lateral ends.

Operation of the separating and conveying device 2 according to the invention is described hereunder with reference to FIGS. 5-14.

As shown in FIG. 5, in an initial situation two piles 13 and 13′ supported side by side on the horizontal accumulation surface 14 are formed at the output of the folding unit 1. The separator-pushers 19 are in the resting position. The two pairs of outer carriages (24 a, 24 b and 24 a′, 24 b′ are at the beginning of the sloping conveying surface 20 and the two pairs of inner carriages 24 c, 24 d and 24 c′, 24 d′ are in an intermediate position of the sloping conveying surface 20.

The actuators of the front carriages 24 b and 24 b′, disposed on the outer sides of the guide bars 22 and 22′, are operated. As a result the pistons 29 of the front carriages 24 b and 24 b′ are raised and the respective racks 31 pass through the longitudinal slots 21 of the sloping conveying surface protruding upward therefrom. In this situation the outer rear carriages 24 a and 24 a′ are blocked on the respective guide bars 22 and 22′, whilst the sleeves 28 of the front outer carriages 24 b and 24 b′ are free to slide on the respective rods 27, drawn by the respective belt or chain 40, to allow the forward movement of the piles of table tissues 13 and 13′. When a predetermined number of table tissues to form a family-size pack have been collected in the two piles 13 and 13′, as shown in FIGS. 6 and 7, the separator-pushers 19 come into action.

Thus, the separating plates 18 of the pushers 19 rotate downwards, separating the two packs 113 and 113′ containing a predetermined number of table tissues. The pistons 17 of the pushers subsequently move forwards pushing the packs 113 and 113′ forwards and slightly compressing them.

At this point the pistons 29 of the rear outer carriages 24 a and 24 a′ are raised causing the raising of the relative racks 31 which place themselves behind the end of packs 113 and 113′ and the carriages 24 a and 24 a′ are released by the respective guide bars.

At the same time, the jaws of the sleeves 28 of the outer front carriages 24 b and 24 b′ are blocked on the respective rods 27. As a result, the pair of outer carriages 24 a and 24 b and the rod 27 form a first monolithic unit which can translate on the first bar 22, whilst the other pair of outer carriages 24 a′ and 24 b′ and the relative rod 27 form a second monolithic unit which can translate on the second bar 22′, driven by the respective belt or chain transmissions 40, so as to convey the packs 113 and 113′ between the respective racks 31, on the sloping conveyor surface 20, up to the tilting conveyor surface 120 in the packaging station 5. In this situation, the tilting conveyor surface 120 is inclined with the same slope as the sloping conveyor surface 20.

Meanwhile, by means of the respect chain transmissions, the two inner front carriages 24 d and 24 d′ are made to translate backwards, drawing with them also the respective rear inner carriages 24 c and 24 c′, until they reach the beginning of the conveyor surface 20, in position awaiting a new pack (FIG. 7).

It should be noted that during the return stroke of the inner carriages (24 c, 24 c′, 24 d, 24 d′), their racks 31 are lowered to pass beneath the racks 31 of the outer carriages (24 a, 24 a′, 24 b, 24 b′) which are raised.

In the packaging station 5, the front plate 50 is in its raised position to allow the two packs 113 and 113′ to pass, whereas the upper plate 52 is in its lowered position, so that the first pack 113 is situated between the side plates 53 and 54 and the side plate 54 acts as a dividing wall between the first pack 113 and the second pack 113′.

It should be noted that at the beginning of the sloping conveying surface 20 the separator-pushers 19 have returned to the resting position with their separating plates 18 facing outwards and the racks 31 of the inner front carriages 24 d and 24 d′ are raised.

At this point, the actuator 122 (FIG. 2) of the tilting conveyor surface 120, which is brought into a horizontal position as shown in FIG. 9, is operated. The front plate 50 is lowered by means of the actuator 58 and the piston 61 is extracted by means of the actuator 59, pushing the rear plate 51 against the head of the packs 113 and 113′ and compressing them, since the end of the packs 113 and 113′ abuts against the front plate 50. Thus, the racks 31 of the outer carriages (24 a, 24 a′, 24 b, 24 b′) are lowered.

FIG. 10 illustrates the compressing operation on the packs 113 and 113′ from another angle. It should be noted that in this situation, the pistons 56, 61 and 64 of the respective actuators 58, 59 and 62 of the front plate 50, of the rear plate 51 and of the top plate 52 are in the extracted position and the support 65 of the actuator 62 is in the end-of-stroke position towards the outside of the machine on the transverse arm 66. The support 65 of the actuator 62 can be operated in translation by a pneumatic actuator without a rod.

As shown in FIG. 11, the actuator 62 is operated and then the support 65 translates along the transverse arm 66 towards the inside of the machine. As a result the pack 113′ which is on the inside position is pushed sideways by the lateral ejection plate 54 which ejects it from the tilting surface 120 transferring it onto the central conveyor 7 (FIG. 1). At the same time the other side plate 53 pushes sideways the pack 113, which was in the outside position, into the inside position previously occupied by the pack 113′.

At this point, the actuator 62 is operated, which retracts the piston 64 raising the upper plate 52 together with the two side plates 53 and 54. Subsequently the actuator 62 is operated, which makes the support 65 of the actuator 62 translate outwards on the transverse arm 66, until it is brought into the end-of-stroke position as shown in FIG. 12. In this situation the remaining pack 113 is on the tilting surface 120 in the inside position, ready to be ejected onto the central conveyor 7.

At this point, as shown in FIG. 13, the piston 64 of the actuator 62 is extracted, causing the upper plate 52 and the two side plates 53 and 54 to be lowered. The actuator 62 is then operated, causing the support 65 of the actuator 62 to translate inwards on the transverse arm 66. As a result, the innermost side plate 54 pushes the pack 113, ejecting it from the tilting surface 120 on the central conveyor 7.

FIG. 14 illustrates the position of the carriages 24 during the step of ejecting the last pack 113. It must be considered that during the step of ejecting the packs 113′ and 113, two new packs 213 and 213′ have been created and are situated between the racks 31 of the two pairs of inner carriages 24 c, 24 d and 24 c′, 24 d′. The front inner carriages 24 d and 24 d′ are made to advance by means of their chain transmissions, drawing with them the inner rear carriages 24 c and 24 c′ and the new packs 213 and 213′, which reach the input of the packaging station 5.

At the same time the front outer carriages 24 b and 24 b′ are made to move backwards by means of their chain transmissions, drawing with them the rear outer carriages 24 a and 24 a′ until they are positioned in the starting position. During the return stroke of the outer carriages (24 a, 24 a′, 24 b, 24 b′) the racks 31 thereof are lowered and pass beneath the racks 31 of the inner carriages (24 c, 24 c′, 24 d, 24 d′) which are raised. Then the racks 31 of the outer front carriages 24 b and 24 b′, on which the heads of the piles 13 and 13′ being formed abut, are raised.

The aforegoing description has been made in the case of the two outer front carriages 24 b and 24 b′ being operated in synchronism, remaining parallel to each other, and the two front inner carriages 24 d and 24 d′ also being operated in synchronism, remaining parallel to each other. In this case two motorizations can be used, one for the two inner front carriages 24 d and 24 d′ and the other for the two outer front carriages 24 b and 24 b′; in any case these two motorizations must be synchronised with each other to ensure the correct operating cycle of the machine.

However, as shown in FIG. 1, provision can be made for the two front outer carriages 24 b and 24 b′ to work offset from each other along the conveyor surface 20 and also for the two front inner carriages 24 d and 24 d′ to work offset from each other along the conveyor surface 20. In this case, however, the motorizations of the front carriages (24 b, 24 b′, 24 d, 24 d′) must be synchronised so that at the input of the packaging station 5, the front carriages (24 b, 24 b′, 24 d, 24 d′) return parallel with each other, so as to ensure that two packs of table tissues enter the packaging station 5 simultaneously.

Numerous modifications of detail within the reach of a person skilled in the art can be made to the present embodiment of the invention without departing from the scope of the invention as set forth in appended claims. 

1. A device (2) for separating and conveying towards a packaging station (5) a predetermined number of flat objects fed in piles (13, 13′) from a folding unit (1), the device (2) comprising: a conveying surface (20, 120) provided with a plurality of longitudinal through slots (21), a plurality of shoes or carriages (24) mounted slidably on guides (22, 23) beneath the conveying surface, a plurality of racks (31) mounted movable on said carriages (24) to pass from a lower lowered position beneath said conveying surface (20, 120) to a raised position in which the prongs (32) of the racks pass through the longitudinal slots (21) of the conveying surface (20, 120) to protrude upward therefrom, wherein said racks (31) are operated so as to separate, from a pile being formed (13, 13′), a predetermined number of flat objects to form a pack (113, 113′) between a pair of racks (31) supported by a respective pair of carriages (24) which are made to translate on their guides so as to convey the pack (113, 113′) towards the packaging station (5), and wherein the device (2) comprises a plurality of pairs of carriages (24), each pair consisting of a rear carriage (24 a, 24 a′, 24 c, 24 c′) and a front carriage (24 b, 24 b′, 24 d, 24 d′), wherein the front carriage is driven by a motorization and connecting means (27, 28) are provided to constrain integrally the rear carriage to the front carriage.
 2. (canceled)
 3. A device (2) according to claim 1, characterized in that said connection means (27, 28) comprise a rod (27) connected to said rear carriage (24 a, 24 a′, 24 c, 24 c′) and protruding forward therefrom substantially parallel to the guides (22, 22′) and a sleeve (28) provided in said front carriage (24 b, 24 b′, 24 d, 24 d′) to slide on said rod (27), said sleeve (28) comprising locking means to be locked integrally in position on said rod (27).
 4. A device (2) according to claim 1 characterized in that said guides comprise a pair of guide bars (22, 22′) parallel to said conveying surface (20, 120) and parallel and spaced apart from each other so as to leave a space (23) within which said carriages (24) can slide.
 5. A device (2) according to claim 3, characterized in that it comprises four pairs of carriages (24): a first pair (24 a, 24 b), disposed on the outer side of the first guide bar (22), a third pair (24 c′, 24 d′) disposed on the inner side of the second guide bar (22′) and a fourth pair (23 a′, 24 b′) disposed on the outer side of the second guide bar (22′).
 6. A device (2) according to, claim 1 characterized in that each rack (31) is supported by a traverse bar (30) which cantilevers on a shaft (29) of a linear actuator provided on the respective carriage (24).
 7. A device (2) according to claim 5, characterized in that each rack (31) has a width equal to about half the width of said conveyor (20, 120) and the transverse bars (30) of the outer carriages (24 a, 24 b, 24 a′, 24 b′) cantilever inward, whereas the transverse bars (30) of the inner carriages (24 c, 24 d, 24 c′, 25 d′) cantilever outward, wherein the height of each rack (31) is less than the extension of the shaft (29) when the racks (31) are in a raised position.
 8. A device (2) according to claim 1 characterized in that each carriage (24) comprises pairs of wheels (25) which run on tracks (125) disposed above and below on said guides (22, 22′).
 9. A device (2) according to claim 1 characterized in that upstream of said conveying surface (20, 120) separator-pushing means (19) able to separate from said plies (13, 13′) a predetermined number of flat objects and to push them forwards on the conveying surface (20, 120) are provided.
 10. A device (2) according to claim 8, characterized in that said separator-pushing means (19) comprise a pair of separating plates (18) mounted on respective pistons (17) mounted retractably, extendably and rotatably in respective cylinders (16).
 11. A device (2) according to claim 1 characterized in that said conveying surface (20, 120) comprise a slightly downward sloping conveying surface (20) and a tilting surface (120) disposed beneath the packaging station (5) and hinged to said sloping conveying surface (20) to pass from an inclined position with a slope equal to that of the sloping conveying surface (20) to a horizontal position.
 12. A device (2) according to claim 10, characterized in that said tilting surface (120) is operated by a linear actuator (122) disposed at its end.
 13. A device (2) according to claim 1 characterized in that said packaging station (5) comprises a vertically movable front plate (50), a horizontally movable rear plate (51) and an upper plate (52) integrally supporting two side plates (53,54) said upper plate (520 being vertically and transversally movable.
 14. A method of separating and conveying towards a packaging station (5) a predetermined number of flat objects fed in piles (13, 13′) from a folding unit (1) using a device (2) as claimed in claim 1, the method comprising the following steps: separating from a bile being formed (13, 13′) a predetermined number of flat objects so as to form a pack (113, 113′) between a pair of racks (31) supported by a pair of carriages (24) sliding on guides (22, 22′) in which said racks comprise prongs (32) which pass through slots (21) formed in a conveying surfaces (20, 120) and conveying the pack (113, 113′) between the pair of racks (31) by means of translation of the respective pair of carriages (24) on the guides (22, 22′) towards the packaging station (5); said separation step taking place by means of a raising movement of said racks (31) and by means of the action, on said pile being formed (13, 13′), of separating and pushing means (19) disposed upstream of said conveying surface.
 15. (canceled)
 16. A method according to claim 13, characterized in that said conveying step comprises the step of integrally constraining said pair of carriages (24) consisting of a rear carriage (24 a, 24 a′, 24 c, 24 c′) and a front carriage (24 b, 24 b′, 24 d, 24 d′), and moving at least on of said two carriages constrained to each other.
 17. A method according to claim 14, characterized in that said conveying surface (20, 120) is able to convey two parallel lines of packs (113, 113′), in that said packaging station is able to receive a pair of packs (113, 113′) and in that said carriages (24) are synchronized so as to convey said packs (113, 113′) side by side or offset from each other.
 18. A method according to claim 15, characterized in that two pairs of carriages (24) act alternately on each line of said conveyor (20, 120).
 19. A method according to claim 16, characterized in that said conveying surface (20, 120) comprises a slightly downward sloping surface (20) tilting surface (120), wherein said tilting surface passes from a position with a slope equal to that of the sloping surface (20) when the packs (113, 113′) are conveyed into the packaging station (5) to a horizontal position, when the packs (113, 113′) are compressed and ejected from the packaging station (5).
 20. A method according to claim 17, characterized in that said packaging station comprises a vertically movable front plate (50) and a horizontally movable rear plate (51) and in that said packaging step entails: lifting of the front plate (50) to allow the pack (113, 113′) to pass, lowering of the front plate (50) and rearward movement of the rear plate (51) to compress the pack (113, 113′), wherein during said packaging step the carriages (24) return to their starting position to pick up a new pack.
 21. A method according to claim 18, characterized in that said packaging station further comprises an upper plate (52) integrally supporting two side plates (53, 54), and in that said packaging step further entails: lowering of said upper plate (52) so that a first pack (113′) is positioned between the two side plates (53, 54) to be compressed, a sideways movement of said upper plate (52) so that the first pack (113′) is transferred to an outlet conveyor (7), a raising and sideways movement of said upper plate (52) so as to bring it into register with a second pack (113),—of said upper plate (52) so that the second pack (113) is situated between the two side plates (53, 54), a sideways movement of said upper plate (52) so that the second pack (113) is transferred to the outlet conveyor (7). 